<h2>DESCRIPTION</h2>

<em>r.plane</em> creates a tilted plane raster map given user-specified
parameters for inclination, azimuth, and the geographic location of a
point on the plane.<br>
The angle orientations of the <em>azimuth</em> parameter increase counter-clockwise,
i.e., 0 degree = N, 45 degree = NW, 90 degree = W etc.
<p>
Increasing values of the <em>dip</em> parameter progressively lower (or dip) the northern
half of the plane, and incline the southern half, assuming the <em>azimuth</em> parameter 
is held constant at 0 degrees.


<h2>NOTES</h2>

<tt>g.region -c</tt> provides the easting and northing coordinates for
the center of the current region.
<p>
<em>CELL</em> (integer) maps take less disk space than <em>FCELL</em>s (floating point),
which in turn take up less space than <em>DCELL</em>s (double precision floating point).
<!-- is that true because of grass's compression? otherwise both int and float are both 4 bytes per cell -->


<h2>EXAMPLE</h2>

A tilted plane in the North Carolina sample dataset region:

<div class="code"><pre>
# set computational region
g.region raster=elev_lid792_1m -p

# get center coordinates as an example
g.region -c
# get terrain height at point
r.what map=elev_lid792_1m coordinates=638650.0,220375.0
# shows elevation: 116.7734

# generate tilted plane
r.plane myplane30 dip=30 az=75 east=638650.0 north=220375.0 \
        elev=116.7734 type=FCELL
</pre></div>

<div align="center" style="margin: 10px">
<a href="r_plane_3d.png">
<img src="r_plane_3d.png" width="600" height="360" alt="r.plane example" border="0">
</a><br>
<i>Figure: Tilted plane shown in NVIZ along with elevation map</i>
</div>


<h2>AUTHOR</h2>

Stefan J&auml;ger (1994), University of Heidelberg during a stay at USGS<br>
Updated to GRASS 5.7 by Michael Barton, Arizona State University<br>
Full rewrite for GRASS 7 by Glynn Clements

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